fungi

Question 1

what is mycosis?

Answer 1

infections caused by fungi

mycosis = in humans and other animals, an infection caused by any fungus that invades the tissues, causing superficial, subcutaneous, or systemic disease.

Question 2

describe the structure of fungi cels

Answer 2

Eukaryotic

Chitinous cell wall

Question 3

how do fungi spread/move?

Answer 3

Move by means of growth or through the generation of spores, which are carried through air or water

Question 4

what are yeasts?

Answer 4

Yeasts are small single celled organisms that divide by budding

type of fungi

Question 5

what are moulds?

Answer 5

type of structure fungi can form

forms from multicellular hyphae (branching structures) and spores

Question 5

what are moulds?

Answer 5

type of fungi

Question 6

what are dimorphic fungi?

Answer 6

fungi that exist as both yeasts and mould, s switching between the two when conditions suit

Question 7

why do fungi struggle to affect humans ie. to cause human mycoses ?

Answer 7

Can’t grow at 37 degrees
Can’t evade our immune responses

Question 8

which is more common? a superficial or invasive fungal disease?

Answer 8

Superficial fungal infection → very common
Invasive fungal infection → rare but easily missed

Question 9

Examples of common but mild fungal infections:

Answer 9

Nappy rash

Vulvovaginal candidiasis (thrush)

Tinea pedis (athlete’s foot)

Onychomycosis (fungal nail infections)

Otitis externa

Fungal asthma

Question 10

Examples of life threatening fungal disease:

In Immunocompromised hosts

Answer 10

Candida line infections (IV lines)

Invasive aspergillosis (a common mould, breathed in by most people without getting ill)

Pneumocystis

Cryptococcosis

Mucormycosis

Question 11

Example of life threatening fungal disease:

Post-surgical patients

Answer 11

intra-abdominal infection

Question 12

Example of life threatening fungal disease:

healthy hosts

Answer 12

Fungal asthma

Travel associated fungal infections

Dimorphic fungi

Post-influenza aspergillosis

Question 13

what are often the drawbacks of fungal diagnostic techniques?

Answer 13

often insensitive in early stages of infection

can be poorly specific

work well for yeasts and less well for moulds eg. culture

have to request them specifically

Question 14

list some diagnostic techniques to identify fungi

Answer 14

radiology

microscopy

culture

PCR tests

antigen tests

Question 15

fungal disease treatment work via selective toxicity

what is meant by selective toxicity?

Answer 15

Aim of antimicrobial drug therapy is to achieve inhibitory levels of agent at the site of infection without host cell toxicity

Question 16

Fungi can be challenging to treat as we have relatively few classes of agent effective against them

name the drug that used to be the mainstay treatment for fungal disease treatment ?

Answer 16

Amphotericin B

Question 17

how does Amphotericin B work and why is it no longer preferred as treatment for fungal infections?

Answer 17

Forms a pore in the membrane, disrupts membrane proteins

Used to be mainstay drug, is very broad spectrum with a high barrier to resistance

but:
- IV only
- Has significant Adverse effects

Question 18

name a commonly used treatment for candida fungi

what is its drawback?

Answer 18

Echinocandins

Iv only

Question 19

what drugs are the current mainstay antifungal therapy?

Answer 19

Azoles

eg. fluconazole

Question 20

Azoles are relatively safe drugs however they do have what potential adverse effects with long term use?

Answer 20

• hepatitis
• alopecia
• GI symptoms eg. abdominal pain
• visual disturbance

Question 21

Azoles are relatively safe drugs however they do have several drug-drug interactions to be aware of

Interfere with metabolism of other drugs, and other drugs can interfere with azole metabolism , largely as a result of cytochrome P450 isoforms

list some key interactions

Answer 21

fluconazole
- interacts with Warfarin

itraconazole
- interacts with statins and steroids

Question 22

what fungi causes infections of toenails

Answer 22

onychomycosis

Caused by dermatophyte moulds

Question 23

what does it mane if a test comes back Beta-D-glucan positive

Answer 23

Beta-D-glucan is a cell wall component of many fungi

therefore this result shows a fungi is present

is a non-specific result